I have and 89 Formula and have seen a few pics of other firebirds with tinted tail lights. I would like to do that to mine but not sure how to do it. Do you have to take them off? or is there a spray tint to use? Anyone have any ideas let me know. Thanks!

 

There is a spray that you can get at any parts store in the spray paint section. I would take them off and clean them well before doing anything. I did it a few years back on my Tahoe and they still look good.
Be mindful that the more passes you make the darker they get. I did two fairly heavy coats on my truck and they are very dark. I put new bulbs in at the same time to make sure I wouldn't have any issues with the authorities.

 

If you have a paint gun you can tint them with clear coat. Clean the lights up real good, sand them with 1000 grit, then spray them with clear coat mixed with a tiny amount of black. They'll look like they were tinted from the factory.

 

Easier said than done!
I tried doing it with spray bomb and had no luck at all with that.I sent 2 sets out to a friend of mine(Body Shop)and had them done,1 set tinted and the other set just clear coated.
This is the spare set that is Tinted lightly.

 

Had a pair done with the black mixed I to clear method. Had it darker than factory to cover de lamination but it holds up great. Still has a good shine a few months later, won't get that with a rattle car